| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CAFPAmTQ3su_tuwHEBKPwn4YFX8sWs0x1agYfyzTnOdBaVRL21Q@mail.gmail.com>
Date: Tue, 22 Nov 2011 13:33:42 -0500
From: "kautuk.c @samsung.com" <consul.kautuk@...il.com>
To: Russell King <linux@....linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>, Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1 v5] arm: fault.c: Port OOM changes into do_page_fault
Please disregard this one due to the following line :
From: Kautuk <kautuk@...ntu.(none)>
There was something wrong in my git configuration.
On Tue, Nov 22, 2011 at 1:16 PM, Kautuk Consul <consul.kautuk@...il.com> wrote:
> From: Kautuk <kautuk@...ntu.(none)>
>
> Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
> (mm: retry page fault when blocking on disk transfer) and
> commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
> (x86,mm: make pagefault killable)
>
> The above commits introduced changes into the x86 pagefault handler
> for making the page fault handler retryable as well as killable.
>
> These changes reduce the mmap_sem hold time, which is crucial
> during OOM killer invocation.
>
> Port these changes to ARM.
>
> Without these changes, my ARM board encounters many hang and livelock
> scenarios.
> After applying this patch, OOM feature performance improves according to
> my testing.
>
> Signed-off-by: Kautuk <kautuk@...ntu.(none)>
> ---
> arch/arm/mm/fault.c | 58 ++++++++++++++++++++++++++++++++++----------------
> 1 files changed, 39 insertions(+), 19 deletions(-)
>
> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> index aa33949..4aabeae 100644
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -231,7 +231,7 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
>
> static int __kprobes
> __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
> - struct task_struct *tsk)
> + unsigned int flags, struct task_struct *tsk)
> {
> struct vm_area_struct *vma;
> int fault;
> @@ -253,18 +253,7 @@ good_area:
> goto out;
> }
>
> - /*
> - * If for any reason at all we couldn't handle the fault, make
> - * sure we exit gracefully rather than endlessly redo the fault.
> - */
> - fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
> - if (unlikely(fault & VM_FAULT_ERROR))
> - return fault;
> - if (fault & VM_FAULT_MAJOR)
> - tsk->maj_flt++;
> - else
> - tsk->min_flt++;
> - return fault;
> + return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
>
> check_stack:
> if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
> @@ -279,6 +268,9 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
> struct task_struct *tsk;
> struct mm_struct *mm;
> int fault, sig, code;
> + int write = fsr & FSR_WRITE;
> + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
> + (write ? FAULT_FLAG_WRITE : 0);
>
> if (notify_page_fault(regs, fsr))
> return 0;
> @@ -305,6 +297,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
> if (!down_read_trylock(&mm->mmap_sem)) {
> if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
> goto no_context;
> +retry:
> down_read(&mm->mmap_sem);
> } else {
> /*
> @@ -320,14 +313,41 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
> #endif
> }
>
> - fault = __do_page_fault(mm, addr, fsr, tsk);
> - up_read(&mm->mmap_sem);
> + fault = __do_page_fault(mm, addr, fsr, flags, tsk);
> +
> + /* If we need to retry but a fatal signal is pending, handle the
> + * signal first. We do not need to release the mmap_sem because
> + * it would already be released in __lock_page_or_retry in
> + * mm/filemap.c. */
> + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
> + return 0;
> +
> + /*
> + * Major/minor page fault accounting is only done on the
> + * initial attempt. If we go through a retry, it is extremely
> + * likely that the page will be found in page cache at that point.
> + */
>
> perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
> - if (fault & VM_FAULT_MAJOR)
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, addr);
> - else if (fault & VM_FAULT_MINOR)
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, addr);
> + if (flags & FAULT_FLAG_ALLOW_RETRY) {
> + if (fault & VM_FAULT_MAJOR) {
> + tsk->maj_flt++;
> + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
> + regs, addr);
> + } else {
> + tsk->min_flt++;
> + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
> + regs, addr);
> + }
> + if (fault & VM_FAULT_RETRY) {
> + /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
> + * of starvation. */
> + flags &= ~FAULT_FLAG_ALLOW_RETRY;
> + goto retry;
> + }
> + }
> +
> + up_read(&mm->mmap_sem);
>
> /*
> * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
> --
> 1.7.5.4
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists